Cryo-EM visualization of an active high open probability CFTR ion channel
Cryo-EM visualization of an active high open probability CFTR ion channel
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活性高开放概率 CFTR 离子通道的冷冻电镜可视化
DOI：
10.1101/274316
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
James Z. Chen
中科院分区：
文献类型：
--
作者：
J. Fay;Luba A. Aleksandrov;T. Jensen;Liying Cui;Joseph N. Kousouros;Lihua He;A. Aleksandrov;Drew S. Gingerich;J. Riordan;James Z. Chen
囊性纤维化跨膜传导调节因子（CFTR）阴离子通道是ATP结合盒转运蛋白大家族的独特成员，其对上皮盐和水的稳态至关重要，并且由于囊性纤维化患者中其基因突变而存在缺陷。CFTR通道活性的调节受到磷酸化和核苷酸结合的严格控制。活跃和不活跃的功能状态之间的转换的基础结构变化尚未完全理解。事实上，第一个去磷酸化，ATP自由和磷酸化ATP结合状态的三维结构只是最近报道的。在这里，我们已经确定了具有非常高的通道开放概率的热稳定CFTR的非活性和活性状态的结构，在重组成脂蛋白体后得到证实。我们观察到的TMH和R结构域密度的独特重新定位为CFTR的活性和非活性功能状态之间的结构转变提供了见解。分别在4.3 nm和6.6 nm分辨率下显示脱磷酸化或磷酸化形式的热稳定禽类CFTR的结构。与斑马鱼和人CFTR结构相比，跨膜螺旋7和8的构象差异揭示了可以提供阴离子进入孔的细胞外前庭。R-结构域密度似乎“堵塞”脱磷酸化的禽类CFTR cryo-EM图中的细胞间前庭。
The Cystic fibrosis transmembrane conductance regulator (CFTR) anion channel, crucial to epithelial salt and water homeostasis, and defective due to mutations in its gene in patients with cystic fibrosis is a unique member of the large family of ATP-binding cassette transport proteins. Regulation of CFTR channel activity is stringently controlled by phosphorylation and nucleotide binding. Structural changes that underlie transitions between active and inactive functional states are not yet fully understood. Indeed the first 3D structures of dephosphorylated, ATP-free and phosphorylated ATP-bound states were only recently reported. Here we have determined the structure of inactive and active states of a thermally stabilized CFTR with very high channel open probability, confirmed after reconstitution into proteoliposomes. The unique repositioning of the TMHs and R domain density that we observe provide insights into the structural transition between active and inactive functional states of CFTR. Highlights Structures of thermostabilized avian CFTR in dephosphorylated or phosphorylated forms at 4.3 Å and 6.6 Å resolution, respectively. Conformational differences of transmembrane helices 7 & 8 compared to zebra fish and human CFTR structures reveal an extracellular vestibule that may provide anion access to the pore. R-domain density appears to “plug” the intercellular vestibule in the dephosphorylated avian CFTR cryo-EM map.
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影响因子：
2.9
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通讯作者：
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影响因子：
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作者：
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